1. Field of Invention
This invention relates to natural language processing.
2. Description of Related Art
Natural language speech offers a number of advantages over conventional keyboard, tactile and other interfaces. Natural language interfaces are among the earliest interfaces learned. Natural language interfaces are among the most intuitive interfaces for users which may reduce cognitive effort in accomplishing certain tasks.
Many command and control systems, knowledge repositories and order taking systems already benefit from conventional natural language speech interfaces. However, these conventional information retrieval systems lack any notion of how to facilitate user interaction. Instead, these conventional systems impose a protocol of interaction on the user. Typically the interaction protocol is created by the interface designer and assumes that the task dialogue is the focus of the user's attention.
In contrast, human-human dialogue uses prosodic features and sequences of discourse functions to indicate appropriate speech presentation strategies. For example, prosodic features and discourse function sequences indicate the turn sequences in the exchange of information. Silences following speech utterances may be used by one dialogue participant to indicate an expected response from another participant. Changes in pitch frequency, rate of speech and/or other prosodic features can be used to indicate questions and/or interrogatory remarks. Similarly, patterns of speech, characteristic discourse functions sequences and/or other presentation strategies are used to indicate turns in the dialogue.
Conventional human-computer natural language interfaces lack appropriate interaction models. That is, conventional natural language interfaces merely present speech information as requested and/or accept speech information when it is presented. A user of a conventional human-computer natural language interface must therefore devote cognitive resources to understanding the appropriate timing and turn taking necessary to interact with these conventional interfaces.
For example, some information retrieval systems implementing these conventional natural language interfaces accept certain types of information only at specified time intervals or only in response to certain prompts. When an information request is received, these conventional information retrieval systems immediately schedule the presentation of the requested information. That is, these conventional systems assume that the human-computer dialogue is the primary dialogue. The immediate presentation of information can distract the focus of attention if the user is interacting with human and/or devices controlled by conventional natural language interfaces. The re-direction of the user's attention creates cognitive thrashing as the user attempts to switch between partially completed tasks.
In human-human interactions, the competition for the user's focus of attention is mediated by the interaction model of the human speakers. However, when the user interacts with systems that lack appropriate interaction models, a greater cognitive load is imposed since the user is forced to follow the interaction model of the system. The user's attention is re-directed from completing the task, to the specifics of how to complete the task. These shifts in the focus of attention reduce the effectiveness of these conventional natural language interfaces. As the number of devices incorporating these conventional natural language interfaces increase, these focus of attention problems also increase.